The bioelectrical properties of pancreatic islet cells: Effect of diabetogenic agents
The Bioelectrical Properties of Pancreatic Islet Cells: Effect of Diabetogenic Agents
0 D e p a r t m e n t of Pharmacology, University of Cambridge , Hills Road, Cambridge, England
Summary. Alloxan 5 mM depolarised the islet b u t not the aeinar cells of mouse pancreatic segments in vitro. This effect was prevented b y D-glucose b u t not b y glutathione, 3, 0, methyl-e-D-glucose, D-glucosamine, D-mannoheptulose, or L-leucine. P r e t r e a t m e n t of islet /?-cells with streptozotocin 20 mM caused no depolarization b u t inhibited the generation of action potentials b y D-glucose, L-leueine, D-mannose and D-glyceraldehyde, whereas tolbutamide-induced action potentials were not blocked ; the alkylating moiety of streptozotocin, N-nitroso N- m e t h y l urea produced similar effects. Prior exposure of the islet cells to nicotinamide 4.1 mM conferred protection against streptozotoein action. These observations are discussed in relation to the diabetogenic action of alloxan and streptozotocin.
Alloxan; D-glucose protection; islet cell potentials; D-mannoheptulose; mouse pancreas; nieotiaamide protection; streptozo~ocin; N-nitroso; N-methyl
Propridt~s biodlectriques des cellules des ~lots pancrdatiques: Effets des agents diabdtog~nes
Rgsumd. L'alloxane (5 raM) a d6polarisd les cellules
des ilots, mais non les cellules de l'acinus des segments
pancrdatiques chez la souris in vitro. Cet effet 6tait
anihil6 par le D-glucose, mais non p a r le glutathion, le 3, 0,
mdthyl-~-D-glueose, la D-glucosamine, le
D-mannoheptulose ou la L-leucine. Le pr6-traitement des eellules fl
des ilots ~ la streptozotoeine (20 mM) n ' a pas provoqu6 de
d6polarisation, mais a inhibd la gdngration de potentiels
d'action par le D-glucose, la L'leueine, le D-mannose et la
D-glyc6ralddhyde, tandis que les potentiels d'action
provoqu~s par la t o l b u t a m i d e n'dtaient pus bloquds; la
partie a l k y l a n t e de la strep~ozotoeine, la
N-nitroso-Nm g t h y l ur6e produisaient les mgmes effets. L'exposition
prdalable des cellules des ilots ~ l'amide nicotinique (4.1
mM) fournissait une protection contre l'aetion de la
streptozotoeine. Ces observations sont diseut~es en
relation avee Faction diabdtoggne de l'Mloxane et de la
The d i a b e t i c s t a t e in an a n i m a l can be i n d u c e d
p o t e n t i a l can be affected b y e x p o s u r e to glucose,
mannose, leueine a n d t o l b u t a m i d e . These substances,
which are also k n o w n to evoke insulin secretion, induce
p e r m a n e n t l y b y t h e selective c y t o t o x i c a g e n t s Mloxan
small a c t i o n p o t e n t i a l s in t h e islet cells
a n d s t r e p t o z o t o e i n . H o w e v e r , t h e m e t a b o l i c a b n o r m a l
M a t t h e w s , 1970a; M a t t h e w s a n d Dean, 1970)
ities of d i a b e t e s m e l l i t u s i n d u c e d b y these c o m p o u n d s
in t h e ionic c o m p o s i t i o n of the e x t r a c e l l u l u r fluid can
are n o t identical, suggesting t h a t t h e y h a v e a different
influence t h e electrical c h a r a c t e r i s t i c s of t h e a c t i o n
m e c h a n i s m of a c t i o n
( N a n s f o r d a n d Opie, 1968)
Allop o t e n t i a l s
(Dean a n d M a t t h e w s , 1970b)
. I n this p a p e r
x a n is speeificMly t a k e n u p b y mouse islet tissue a n d
t h e effects of Mloxan a n d s t r e p t o z o t o c i n on mouse
paneytologieM changes are visible in fi-eells w i t h i n 5 m i n
ereatic islet cell m e m b r a n e p o t e n t i a l s a n d on electrical
of Mloxan a d m i n i s t r a t i o n
(I-Iammarstrom, t I e l l m a n
a c t i v i t y are described. A p a r a l l e l s t u d y has been m a d e
a n d Ullberg, 1966; L a z a r u s , B u r d e n a n d B r a d s h a w ,
of t h e a c t i o n of t h e c o m p o u n d N - n i t r o s o N - m e t h y l
. The r a p i d increase in the r a t e of p e n e t r a t i o n of
urea, t h e M k y l a t i n g m o i e t y of s t r e p t o z o t o c i n , on t h e
l t C - m a n n i t o l i n t o t o a d f i s h islets i n d i c a t e d t h a t Mloxan
electrical a c t i v i t y i n d u c e d b y glucose in islet cells.
a l t e r e d t h e p e r m e a b i l i t y of /~-eells
( W a t k i n s ,
Cooperstein a n d L a z a r o w , 1964)
. L i t t l e is k n o w n a b o u t t h e
m e c h a n i s m of i n d u c t i o n of d i a b e t e s b y s t r e p t o z o t o c i n .
E l e e t r o p h y s i o l o g i c a l studies h a v e shown t h a t
fiThe p a n c r e a s was r e m o v e d from albino mice of
cells from mouse p a n c r e a t i c islets h a v e a cellular t r a n s
m e m b r a n e p o t e n t i a l of --20.1 m V a n d t h e resting
either sex weighing 3 0 - - 4 0 g. A s e g m e n t of p a n c r e a s
was p l a c e d in a p e r s p e x tissue b a t h a n d superfused
P.M. Dean and E . K . Matthews: The Bioelectrical Properties of Pancreatic Islet Cells
0 10 20 30 Z,O 50 60
Fig. 1. The effect of alloxan on the membrane potential of
islet cells from mouse pancreas. The first eolum shows the
mean membrane potential obtained during the 60 min
period before addition of alloxan
t r a n s m e m b r a n e potentials according to the methods
(Dean and Matthews, 1970a)
Since alloxan, streptozotocin and N-nitroso
Nm e t h y l urea are rapidly decomposed b y hydrolysis,
solutions of these compounds were made immediately
before use and added directly to the tissue bath.
The possible methylation of nieotinamide b y
streptozotocin was investigated chromatographically.
20 mM streptozotocin and 4.1 mM nicotinamide
solutions were incubated at 37~ for 20 rain and a 100 ~L
aliquot applied to W h a t m a n No. 1 filter paper.
Aliquots (100 ~L) of solutions of nicotinamide 4.1 raM,
N-methylnicotinamide 4.1 mM and 1 m e t h y l
nieotinamide 4.1 mM were used for comparison. The
chromategrams were developed in N-butanol saturated with
water, and the spots visualized after exposure to iodine
Experiments with alloxan
The effect of the addition of alloxan 5 m ~ on
mouse islet cell m e m b r a n e potentials is shown in Fig. 1.
Alloxan did not affect the acinar cell m e m b r a n e
potentials, whereas the islet cells showed a rapid, significant,
and sustained depolarization from --20.8 m V S.E.M.
2.4 m V to - - 8 . 6 m V 4 - S . E . M . 1.3 m V ( P < 0 . 0 1 ) .
G SH GLUCOSE L-LEUCINE MANNOHEPTULOSE 3"O'METHYL D-GLUCOSAMINE
15mM 16.6mM 15 m M 23 .SmM 25"G6LmUMCOSE 23'2 mM
Fig. 2. The histograms show the effectof preineubation of isletcellsfor 15 rain with various compounds, indicated
beneath each histogram. The Ist column shows the m e a n m e m b r a n e potential in normal solution,the 2nd column shows
the effect of alloxan 5 m M after preincubation with a possible protective compound, the m e m b r a n e potentials being
measured during the 30-- 60 min period after alloxan. The inset oscilloscopetraces show electricalactivity during the
preincubation period with glucose 16.6 mM and L-leueine 15 mM
with Krebs-Henseleit solution at 37~ The solution
had the following composition: NaC1 103 raM, KC1
4.7 raM, CaCls 2.56 raM, MgC12 1.13 raM, NaHCOs
25 raM, NaHePO4 1.15 mM, D-glucose 2.8 raM, sodium
p y r u v a t e 4.9 raM, sodium f u m a r a t e 2.7 raM, sodium
glutamate 4.9 raM. I t was gassed with 95% 0 2 - - 5 %
COs. The islets of Langerhans were separated from the
surrounding acinar tissue b y micro-dissection. Glass
micro-electrodes filled with 1.5 M potassium citrate,
tip resistance 100 M f~, were used to record the cellular
Alloxan did not induce electrical activity in islet cells.
Histograms of frequency plotted against m e m b r a n e
potential for impalements obtained during the period
30 to 60 rain after alloxan 5 mM did not reveal a
population of islet cells which were resistant to
depolarization b y alloxan.
The results shown in Fig. 2 are the effects of
preincubation of islets with glutathione 15 mM, I)-glueose
16.6 mM, L-leucine 15 mM, 3,0-methyl-c~-D-glucose
25.6 mM, D-glueosamine 23.2 raM, or
P.M. Dean and E.K. Matthews: The Bioeleetrical Properties of Pancreatic Islet Cells
lose 23.8 mlV[, on the depolarization of islet cells
normally produced b y alloxan 5 raM. The mean m e m b r a n e
potential was measured for impalements obtained
during the control period (60 min) before exposure to
alloxan (this value is shown on the left column of each
histogram). Preincubation with 15 mM g]utathione
15 rain before and during exposure to alloxan 5 mM
did not prevent depolarization (values shown in the
right-hand column of each histogram were obtained
from the period 30--60 min after alloxan
administration). I n contrast, glucose 16.6 mM, produced
complete protection against alloxan. During the
superfusion with glucose 16.6 mM action potentials were
generated in islet cells (Fig. 2). Preincubation with
Lleueine 15 mM, which also induced action potentials,
failed to protect against the depolarization produced
b y alloxan 5 raM. The strnetural analogues of glucose :
3,0-methyl-~-D-glueose, D-glueosamine and
mannoheptulose -- an inhibitor of hexokinase, failed to
prevent the depolarization of islet cells. These drugs when
exposed to the tissue alone, did not produce
Experiments with streptozotocin
Streptozotoein is rapidly inactivated b y hydrolysis
at physiological p I I (Garret, 1960) so t h a t the drug
could not be superfused over islet cells for more t h a n
short time periods.
The islet tissue was perfused for one hour in normal
Krebs-Henseleit solution and numerous islet cells were
impaled in order to determine a mean value for the
m e m b r a n e potential. A dose of steptozotocin was added
directly to the b a t h to achieve an initial concentration
of 20 mM, the m e m b r a n e potentials were measured,
and the mean values obtained for successive 10 rain
intervals. During the 60 rain period after exposure to
streptozotocin the m e m b r a n e potential was unchanged
(Fig. 3) and streptozotoein did not itself induce
electrical activity in islet cells.
Elsewhere it has been shown t h a t D-glucose 11.1
raM, L-leucine 10 raM, D-mannose 16.6 mM and
Dglyceraldehyde 11 mM each induce electrical activity
in islet cells
(Dean and Matthews, 1970a; Matthews
and Dean, 1970; Dean and Matthews, 1971)
. This t y p e
of activity was characterized b y bursts of action
potentials occurring at 10 s intervals; the action
potentials had an amplitude of 1 - - 4 mV and a duration of
50 mS. Tolbutamide 0.7 mM, however, induced
continuous firing of longer duration action potentials at a
rate of a b o u t 1 per sec, 250 ms duration and amplitude
1 - - 8 mV.
The effect of streptozotocin on action potential
generation was studied as follows. Measurements of
islet cell m e m b r a n e potentials were made during a 60
min control period in normal Krebs-I-Ienseleit solution
containing the stimulating agent, e.g. D-glucose 11.1
mN[ and the fraction of impaled cells which produced
electrical activity was noted; this procedure was
repeated on several islet preparations. I n further
experiments, m e m b r a n e potentials were measured during a
control period, then, after a single dose of
streptozototin corresponding to a peak b a t h concentration of 20
mM, m e m b r a n e potentials were measured during the
next 60 min; the preparation was subsequently
superfused for 30 rain with glucose 11.1 mM (or other
stimulating agent) and the fraction of cells exhibiting action
potentials during this 30 rain period was observed. The
results expressed in Table 1 show t h a t p r e t r e a t m e n t
with streptozotoein inhibited the generation of action
potentials b y D-glucose, L-leucine, D-mannose and
D-glyceraldehyde, whereas tolbutamide-induced
action potentials were not blocked b y p r e t r e a t m e n t with
Nicotinamide injected intravenously into mice
protects against the diabetogenic properties of
(Schein and Bates, 1968)
. After obtaining control
values of m e m b r a n e potentials in normal
KrebsHenseleit solution, the cells were exposed to solution
containing nieotinamide 4.1 mM 15 rain before addition
of streptozotocin 20 raM; 60 min later solution
containing glucose 11.1 mM was perfnsed over the tissue
for 30 rain. Glucose induced firing in 83% of the
impaled islet cells showing t h a t nicotinamide conferred
protection against streptozotocin. Exposure to
nieotinamide 4.1 mM alone did not generate action potentials
or change the resting m e m b r a n e potential.
The effect of N-nitroso N - m e t h y l urea was
investigated for comparison with streptozotocin. Membrane
potentials were measured in normal Krebs-Henseleit
solution during a 60 min control period, then N-nitroso
N - m e t h y l urea was added to the b a t h to produce a
D-glucose 11.1 mM
D-mannose 16.6 mM
L-leucine 10 mM
D-glyceraldehyde 11 mM
Tolbutamide 7 10-4M
followed by D- 11.1 mM
u = number of experiments.
P.M. Dean and E.K. Matthews : The Bioelectrical Properties of Pancreatic Islet Cells
peak concentration of 20 mlYi and the preparation was
superfused for 60 min. When the tissue was exposed to
a solution containing D-glucose 11.1 raM, action
potentials were induced in only 3.5% of the cells. On the
other hand with tolbutamide 0.7 m N as a stimulating
agent, action potentials with characteristics typical
of tolbutamide were produced in 50% of the cells.
Paper chromatography showed t h a t incubation of
streptozotocin 20 m N with nicotinamide 4.1 mM
produced a single spot with an RF value of 0.65;
nicotinamide itself had an t~r value of 0.66. No spots were
found corresponding to N-methyl nicotinamide (RF
accompanying changes in islet cell permeability to
(Watkins, Cooperstein and Lazarow, 1964)
In contrast, streptozotocin did not alter islet cell
membrane potentials during the 90 min period of exposure;
the earliest cytological ehanges are apparently
observed only after 2 h
(Brosky and Logothetopoulos,
Of the substances tested, only D-glucose protected
islet cells against depolarization b y alloxan. There is
no evidence for inactivation of alloxan b y glucose
. Since D-glucose, D-fructose and
Dmannose given in vivo protect against alloxan diabetes
(Bhattaeharya, 1953; 1954) and all three hexoses are
0.82) or 1-methyl nieotinamide (RF 0.05). Therefore,
the possibility of simple chemical inactivation of
streptozotoein, with nicotinamide acting as an acceptor
for the free methyl radical, seems unlikely.
Alloxan rapidly and selectively depolarized the
cells from mouse islets of Langerhans. In contrast,
guinea-pig islet cells, which are known to be resistant
to the diabetogenic properties of alloxan
, are not depolarized by Mloxan
and Matthews, 1968)
. The rate of onset of
depolarization b y alloxan, an effect occurring within l0 min,
correlates well with the time course of cytological
changes which are: a diminution in nuclear and
cytoplasmic granules, vacuolation and shrinkage of
cytoplasm (Lazarus, Barden and Bradshaw, 1962), with
metabolized b y hexokinase, it was thought t h a t alloxan
might act b y inhibiting hexokinase. However,
VillarPalasi, Carbadillo, Sols and Arteta (1957) showed t h a t
the ratio of the protective properties of D-glucose,
Dmannose and D-fructose did not correspond to the
affinity of these hexoses for pancreatic hexokinase.
The glucose analogues 3,0-methyl-~-D-glueose and
D-glueosamine did not confer protection, neither did
D-mannoheptulose which is a specific inhibitor of
hexokinase. Since glucose induced action potentials in
islets, the possibility occurred t h a t some property
related to the action potential discharge could have
produced the protection. However, this is improbable
because L-leucine, which also induced action potentials,
did not protect the islet cells from the depolarizing
influence of alloxan. Although glutathione given in vivo
protects against alloxan diabetes
in vitro protection was observed.
~o of cells induced 0/0 of cells induced n
to fire action po- to fire action
potentials by the tentials by the
compound without compound after
pretreatment with pretreatment with
% of cells induced % of cells induced n
to fire action po- to fire action
potentials by the tentials by the
compound without compound after
pretreatment with pretreatment with
N-methyl urea N-methyl urea
P.M. Dean and E.K. Matthews: The Bioelectrieal Properties of Pancreatic Islet Cells
P r e t r e a t m e n t of islet cells with streptozotoein
destroyed the ability of the cells to generate action
potentials when stimulated b y D-glucose, D-mannose,
L-leucine or D-glyceraldehyde. I t has recently been
shown t h a t preincubation of isolated islets of
Langerhans with streptozotoein inhibits glucose-induced
(Golden, Baird, Malaisse,
Malaisse-Lagae and Walker, 1971)
. Induction of electrical activity
with tolbutamide was not inhibited b y streptozotocin.
I n vivo experiments with mice pretreated with
streptozotocin have shown t h a t tolbutamide reduces the
diabetic hyperglycemia, p r o b a b l y b y releasing insulin
( g e r u p and Tarding, 1969)
. Streptozotocin can
therefore distinguish between the two ionic mechanisms in
the fl-cell m e m b r a n e b y inhibiting fast action
potentials characteristic of D-glucose, L-leueine, D-mannose
and D-glyeeraldehyde, whilst not m a r k e d l y affecting
the slower action potentials produced b y tolbutamide.
P r e t r e a t m e n t with nicotinamide protects isolated
r a t islets of Langerhans, and the whole animal, against
the diabetogenic action of streptozotoein
Bates, 1968 ; Sehein, Cooney and Vernon, 1967 ; Golden,
Baird, Malaisse, Malaisse-Lagae and Walker, 1971)
Streptozotoein produces a depression of N A D and
NADI-I levels in mouse liver; this depression is
prevented b y nieotinamide administered before the dose
(Schein and Loftus, 1968)
. I t is not
known, however, whether streptozotoein produces
diabetes b y affecting N A D levels in fi-eells, although
our results and those of Golden et al. (1971) suggest
N-Nitroso N - m e t h y l urea is alleged to be
(Sehein and Loftus, 1968)
. However, in
vitro a single dose of N-nitroso N - m e t h y l urea had a
similar effect to streptozotoein b y inhibiting action
potentials when islet cells were subsequently exposed
to glucose. Similarly N-nitroso N - m e t h y l urea did not
inhibit action potentials generated b y tolbutamide.
The close resemblance between the effects of N-nitroso
N - m e t h y l urea and streptozotoein might suggest a
similar mode of action on islet cells.
The p r i m a r y target for the cellular effect of
streptozotoein is unknown; specific inhibition of the
glueoreceptor appears unlikely since action potentials
elicited with the structurally dissimilar substances,
L-leucine and D-glyeeraldehyde are also blocked. The
mechanism of insulin secretion is not necessarily
destroyed since the hypoglyeemie effect of tolbutamide
and action potential genesis still occur after
pretreatm e n t with streptozotoein. As the effect of
streptozotocin on electrical activity can be mimicked b y N-nitroso
N - m e t h y l urea it is probable t h a t the N-nitroso
Nm e t h y l urea moiety of streptozotoein causes diabetes,
the glucose m o i e t y acting to confer high specificity for
the fl-eell, since these cells m u s t have a very specialized
mechanism for reeognising and handling glucose
Magee and Schoental (1964)
have suggested t h a t
alkyl nitroso compounds react with cell thiol groups
with the eventual liberation of a m e t h y l radical. The
free m e t h y l radical is then able to m e t h y l a t e a n y free
sulphydryl or carboxylie groups.
H o w alloxan causes islet Bells to depolarize is not
y e t known. Inhibition of energy production as the
p r i m a r y effect of alloxan seems improbable because
dinitrophenol, which is believed to inhibit the
production of A T P in m a m m a l i a n cells, does not depolarize
the islet cells
(Dean and Matthews, 1970a)
is normally transported into islet cells, b u t not in cells
obtained from mice resistant to alloxan ( H a m m a r
strom, st al., 1966), suggesting t h a t the cytotoxieity of
alloxan is dependent on uptake into the islets. Since
alloxan causes a rapid permeability change it is
possible t h a t it reacts directly with a specific
membrane component, possibly through the highly reactive
earbonyl grouping at position 5. The binding of glucose
to the m e m b r a n e m a y induce a eonformational change
in the alloxan carrier mechanism, t h e r e b y preventing
alloxan from entering the Bell to exert cytological
(Sehneyius and T/~ljedal, 1971)
. However, the
precise molecular mechanism for the production of
diabetes by either alloxan or streptozotocin remains to
Acknowledgements. This work was supported by a
Medical l~esearch Council research grant to E.K.M.P.M.
D. is a Research Fellow of King's College, Cambridge. We
are grateful to Professor P.N. Magee for the supply of
N-nitroso N-methyl urea and the Upjohn Company
(Kalamazoo) for the supply of streptozotocin.
J ~ f er~nce8
Bhattacharya , G. : Protection against alloxan diabetes by mannose and fructose . Science 117 , 230 -- 231 ( 1953 ).
- - O n the protection of alloxan diabetes by hexoses . Science 120 , 841 -- 843 ( 1954 ).
Brosky , G. , Logothetopoulos , J. : Streptozotocin diabetes in the mouse and guinea-pig . Diabetes 18 , 606 -- 611 ( 1969 ).
Dean , P.M. , Matthews , E . K . : Alloxan on islet cell membrane potentials . Brit. J. Pharmac . 34 , 677 ( 1968 ).
-- -- Glucose -induced electrieM activity in pancreatic islet cells . J. Physiol . 210 , 255 -- 264 ( 1970a ).
-- - - Electrical activity in pancreatic islet cells: effect of ions . J. Physiol . 210 , 255 -- 275 ( 1970b ).
-- - - The effect of some metabolic intermediates on islet cell membrane potentials . Bioehem. biophys. Acta ( 1971 ) in the press.
Garnet , E.R.: Prediction of stability in pharmaceutical preparations. 7. The solution degradation of the antibiotic streptozotocin . J. Amer. Pharm. Assoc . 47 , 767 -- 777 ( 1960 ).
Golden , P. , Baird , L. , Malaisse , W.J. , Malaisse-Lagae , F. , Walker , M. : Effect of streptozotoein on glucose-induced insulin secretion by isolated islets of Langerhans . Diabetes 20 , 513 -- 518 ( 1971 ).
Hammarstrom , L. , Hellman , B. , Ullberg , S. : On the accumulation of alloxan in the pancreatic fl-cells . Diabetologia 2 , 340 -- 345 ( 1966 ).
Lazarow , A. : Protective effect of glutathione and eysteine against alloxan diabetes in the rat . Proe. Soe. exp. Biol. Med . 61 , 441 -- 447 ( 1946 ).
Magee , P.N. , ShoentM , 1 ~. : Carcinogenesis by nitroso compounds . Brit. Med. Bull . 20 , 102 -- 106 ( 1964 ).
Mansford , K. 1 ~.L., Opie , L. : Comparison of metabolic abnormalities in diabetes mellitus induced b y streptozotocin or by alloxan . Lancet 1968 , 670 -- 671 .
Maske , H. , Weinges , K. : U n t e r s u c h u n g e n fiber das Verhalten der Meerschweinchen gegenfiber verschiedenen diabetogenen Noxen. Alloxan u n d Dithizon . Arch. exp. Path. Pharmak . 239 , 406 -- 420 ( 1957 ).
Matthews , E . K . , Dean , P.M. : Electrical activity in islet cells. I n : The Structure a n d metabolism of pancreatic islets . Ed. Falkmer, S. , Hellman , B. , T~ljedal, I . B . Oxford and New York: Pergamon Press 1970 .
Rerup , C. , Tarding , F. Streptozotocin a n d alloxan diabetes in mice . Europ. J. Pharmacol. 7 , 89 -- 96 ( 1969 ).
Schein , P.S. , Bates , R . W . : P l a s m a glucose levels in norm a l a n d adrenaleetomized mice treated with streptozotocin a n d nicotinamide . Diabetes 18 , 760 -- 765 ( 1968 ).
-- Cooney , D.A. , Vernon , M . L . T h e use of nicotinamide to m o d i f y the toxicity of streptozotocin diabetes without loss of autitumour activity . Cancer Res . 27 , 2324 -- 2332 ( 1967 ).
-- Loftus , S.: Streptozotocin: depression of m o u s e liver pyridine nucleotides . Cancer Res . 28 , 1501 -- 1506 ( 1968 ).
Schneyius , A. , T/iljedal, I . B . : On the mechanism of glucose protection against alloxan toxicity . Diabetologia 7 , 252 255 ( 1971 ).
Villar-Palasi , C. , Carbadillo , A. , Sols , A. , Arteta , J . L . : Sensitivity of pancreas hexokinase towards alloxan a n d its modification b y glucose . Nature 180 , 387 -- 388 ( 1957 ).
Watkins , D. , Cooperstein , S.J. , Lazarow , A. Effect of alloxan on permeability of pancreatic islet tissue in vitro . Amer. J. Physiol . 207 , 436 -- 440 ( 1964 ).
Webb , J . L . : Alloxan. I n : E n z y m e a n d metabolic inhibitors . Vol. 3 , p. 390 . New York: Academic Press 1966.